Harvard vs. vonNeuman

From: Dave Dunfield <dave04a_at_dunfield.com>
Date: Tue Sep 28 13:46:05 2004

>Part of the issue, for modern machines, is that the hardware gets in
>the way. If you change code, the I-cache doesn't change (in machines
>I'm familiar with) so the old instruction may still execute. This
>makes instruction modification a tricky business. Debuggers do it,
>operating systems do it -- and both have to pay attention to all the
>cache magic you have to perform for it to be right.

This reminds me of a point I wanted to make earlier and forgot - another
big issue us that SOFTWARE gets in the way! - todays computing world is
much more oriented toward sharing code, and many systems support multiple
execution threads of a single copy in core - it causes bad things to
happen when one of those threads changes the code :-)

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.
Received on Tue Sep 28 2004 - 13:46:05 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:32 BST